In a wireless communication system, a user equipment (UE) may receive data and/or a variety of control information from a base station (BS) on downlink (DL) and transmit data and/or a variety of control information on uplink (UL). To communicate with the BS, the UE needs to establish synchronization with the BS. To this end, the UE, which is powered on again from a power-off state or newly enters a cell which is a geographic region served by a BS, performs initial cell search accompanying operation such as synchronization establishment with the BS. Upon completion of initial cell search, the UE may receive data and/or control information through a physical DL channel and transmit data and/or control information through a physical UL channel.
For various reasons including cell search, maintenance of time synchronization after synchronization between the UE and the BS, and compensation of a frequency offset, a wireless communication system which has been discussed until the present defines transmission/reception of various mandatory signals on designated radio resources.
The types and number of these mandatory signals have increased with the advance of standards of the wireless communication system. Since signals other than the mandatory signals cannot be allocated to radio resources to which the mandatory signals are allocated, the mandatory signals which are increasing in accordance with advances in the wireless communication system hinder the degree of freedom of scheduling of the wireless communication system and also restrict introduction of more efficient communication technology for the wireless communication system.